1. Field of Invention
The present invention relates to an apparatus and method for driving a display device, and more particularly to an apparatus and method for driving a display device via a single driving voltage generating circuit.
2. Description of Related Art
Since liquid crystal display (LCD) has many advantages such as light, thin, short, and small, with low energy consumption and low radiation, it has come to be widely used in recent years.
In the liquid crystal panel of an LCD display, the relationship between the voltage applied to the liquid crystal molecule (referred as driving voltage below) and the light transmittance of a pixel is a gamma curve, rather than a linear relationship. By correcting the gamma curve, the gray scale signal of the pixel and the light transmittance of the liquid crystal molecule can be made to have a near linear relation, thus, the displayed image for an LCD is more desirable.
In an LCD display, each display unit, i.e. a pixel, consists of three sub-pixels. Each sub-pixel is used to display one of the three primary colors of red (R), green (G), and blue (B). Depending on which primary color a sub-pixel displays, the corresponding gamma curve will be different. Referring to FIG. 1a which shows three gamma curves R, G, B, which respectively represent the relationship between the gray scale signals and the light transmittances when the sub-pixel displays red, green, and blue, respectively.
In order to obtain different driving voltages to display red, green and blue, in the conventional technology, three R/G/B look-up tables and three gamma voltage generating circuits are used respectively to obtain three sets of driving voltages corresponding to the R/G/B gray scale signals to drive the liquid crystal molecules. However, this prior art requires a relatively large memory space for storing three look-up tables, and three gamma voltage generating circuits will dramatically increase the area of the drive circuit.
Thus, it is preferred to have an apparatus and method for driving a liquid crystal display, which only needs a relatively small storage space for a look-up table and a gamma voltage generating circuit to generate the required three sets of driving voltages.